Subacute and subchronic intoxication by hydrazines (hydrazine (Hz), monomethylhydrazine (MMH), 1,1-dimethylhydrazine (UDMH) and benzylhydrazine (BH)) will be studied. Where possible we will establish continuous parenteral dose rates which are lethal to half of the treated animals after 24 hours and after 10 days of exposure (LR50(24 hour) and LR50(10 day)). The effect of various levels of sustained intoxication on the capability of test animals to metabolize methylamine-C14, putrescine 1,4-C14, and amino butyric acid-1-C14, will then be observed. Each substrates is metabolized by a system known to be sensitive to some or all of these hydrazines. If possible, a toxic steady-state will be established such that the rate of recovery of activity balances the rate of loss due to intoxication. These observations will be correlated with in vitro measurements of intestinal diamine oxidase (DAO) and brain and liver monoamine oxidase (MAO) following intoxication. Intoxicated animals will be evaluated at intervals following exposure to estimate the rate of recovery of inhibited systems. These studies will provide an index of cumulation of effect an may provide a means of detecting intoxication, in view of already known effects of very low dose rates of MMH on amine metabolism. Effects of the hydrazines on the very active ornithine decarboxylase of regenerating rat liver and the high DAO of rat placenta and pregnancy plasma will also be examined in vivo and in vitro. Conversion of continuously infused labeled substrates to CO14 sub 2 will be measured radiorespirometrically, at selected times during and after intoxication. The measurement system utilizes flow ionization chambers coupled to vibrating reed electrometers, with automatic data acquisition.